Automatic slack adjuster



Feb 25, @936, H, GALLUSSER v 2,@3L74 AUTOMATIC SLACK ADJUSTER Filed Jan. 1o, 1954 2 sheets-sheet 1 .F 11a 74% /0. 7 I

i0. f Q Nn lllV Patented Feb. 25, 1936 UNITED STATES PATENT OFFICE AApplication January 10, 1934, Serial No. 705,992 In Switzerland January 16, 1933 1 Claim.

Different devices for the automatic taking up of the play occasioned by the wear and tear of the brake-shoes or bands, the lengthening of the members of the brake rigging mechanism, etc., are alreadyv known.

The invention relates to such a device which is composed of pawls formed by clamps located on a threaded bar o-f the brake rigging mechanism, each of these clamps consisting of a nut divided in several parts held together by an elastic member, the nut having an exterior conical surface which by theaction of tractive effort, effects the coupling of the threaded bar with the members with which it is intended to cooperate, each clamp being capable of moving between two abutments, onerof which is conical, the distance between the abutments of each clamp being just suiiicient for the disengaging of the clamp from the threads of the bar bearing the clamp.

The device according to the invention comprisestwo clamps, the pair of abutments of one clamp being rigidly connected to the member of the brake rigging with which the threaded bar co-operates, -whilst the pair of abutments of the other clampare connected to a movable member between two adjustable abutments, locatedoutside the device, the two members, each of which bears one of -the pairs of the abutments of a clamp, being cor-axial and capable of meeting each other so as to push each other along.

The drawings show, by way of example two forms of the device embodying the invention.

Figs. 1 and 2 show cross sectional views of a dev vice capable of being fitted to the simple bar of a brake riggingmechanism, with the parts in two different positions,

Figs. 3v to 6 show another form of the invention applicable particularly to the Westinghouse railway vehicle type of brake, with the parts in different positions.

According to the'form illustrated in Figs. land 2, the bar I is intended to transmit a tractive effort to the bar 2 threaded at 3 and connected to the brake members for electing the braking action, said brake members not being illustrated in the drawings. The tractive effort developed by the bar I is transmitted to the bar 2 by means of the clamp 4 of the casing or box 5 which contains it, and by means of the tube 6 which is connected to said box 5 and into which the bar 2, which is co-axial with said tube 6, can enter.

The clamp 4 is movable between two abutments, one of which'is conical as indicated at 1 and the other flat as indicated at 8; it is easily seen, because of the form of the clamp and (Cl. 18S-200) the direction of the saw-tooth threads 3 that if a tractive effort is exerted in the direction of the arrow 9 on the bar I, the bar 2 will be drawn along by the tightening of the different parts of the clamp 4 by the action of the conical abutment I thereon.

Surrounding the aforesaid members is a casing or cylinder I containing a second clamp II capable of being displaced with said members, at least within certain limits determined by the abutment-nuts I2, I3, between which the setting member or arm I4 carried by the cylinder moves. The clamp Ii, facing in the same direction as the clampy 4 is also movable between two abutments, one of which is conical vand the other flat. The abutment-nuts I2 and I3 are disposed on a rod I5. comprising correspondingly threaded parts, and xed in a stationary lug I'I suitably mounted on the chassis of the vehicle,

This is what takes place when the braking action is applied:

A tractive effort is exerted in the direction of thev arrow 9 o-n the bar I, which is transmitted as above described to the clamp 4 and thence, to the bar 2, the latter transmitting it to the braking members, e. g. to the brake shoes. Bar I, bar 2, tube E, box 5 and clamp 4 are therefore dis placed to the right in the drawings, and correspondingly pull the clamp II and the members surrounding it, particularly the cylinder Itl, its bottom I5 and the arm I4 which, leaving its contact with the abutment-nut I2, will slide along the rod I5 at least as far as the space between the abutment-nuts I2 and I3 will allow.

This space between these two nuts must normally be adjusted in such a way that the displacement it allows will be sufcient for a perfect braking action.

Should the braking action, this adjustment being effected, necessitate a greater displacement because of wear and tear on the brake shoes, the different members of the device would reach the positions shown in Fig. 2.

`In this figure, it will be noted, that the arm I4 by engagement with the abutment-nut I3, and the rod I continuing with the rod 2 its braking movement has effected a separation between the box 5 of the clarnpI 4 and the adjacent members surrounding the clamp II. The space I8 thus fo-rmed results from the excess of play in the brake shoes and determines a length, and this is the length by which the bar 2 must be shortened for the purpose of overcoming the said play.

It is to be noted that if the clamp II has been stopped in its movement, and the bar 2 has been able to continue its displacement, this is due to the inclined direction of the saw-tooth form of the threads 3 and to the fact that the clamp II through this operation, has been applied against the flat abutment, so that the segments which form it are free to move away from one another and to thus permit the said bar to move relatively.

The braking action being over, when the bar I returns to its original position, the entire device will be displaced in the same direction, i. e. from right to left in the drawing, and this displacement will continue until the arm I4 meets the abutment-nut I2. At that moment, the bar I will continue its course until the box 5 again engages the members surrounding the clamp II, thus eliminating the space I8. But the bar 2 will not be able to join in this latter part of the movement, because it is held back by the clamp II which does not allow this bar to move from right to left and is at this moment itself held back by the members surrounding it, the cylinder I0, the bottom I5 and the arm I4 in contact with the abutment-nut I2. The clamp 4 on the other hand, because of its direction and the direction of the saw-tooth threads 3 will allow for this moving together of the clamps 4 and II by jumping from thread to thread on the bar 2.

It is now clear that at the next braking action, when the bar I again draws along the bar 2, the whole length of these two bars will be shortened by the space I8 i. e. by the excess of play to be taken up, these operations being repeated every time a taking up action is required.

The fact that the abutments I2 and I3 consist of nuts disposed on a threaded bar, allows the position of these abutments in relation to the extreme positions of a normal braking action to be adjusted exactly.

The Westinghouse brake according to Figs. 3 to 6 comprises a brake cylinder I9 the piston-rod of which acts on a double-lever 20 pivotally movable on the end of a bar 2 I, the other end of which is articulated with a double lever 22 similar to the preceding one, pivotally xed at 23, the two ends 24, 25 of the two double levers acting in the well known way on the braking members.

One of the braking bars 26 is connected to lever 20 at the pivot 24 by means of a device according to the invention, whilst the other bar 21 is connected to the lever 22 as usual at the pivot 25. A bar 28 carrying the two abutment-nuts 29, 30 is also connected to the lever 22 at the pivot 25.

Fig. 3 shows the members out of action with the clamps 3I, 32 occupying the nearest possible position to each other on the threaded part 33 of the bar 26.

Fig. 4 shows the displacement of these different members at the time of a normal braking action i. e. when the brake shoes develop no excess of play: the setting member or arm 34 of the device has moved away from the abutment-nut 29 and is now applied against the abutment-nut 30, the space between these two nuts being so determined as to allow a correct braking action. Moreover as can be seen, the whole device has been displaced from left to right in the drawings, following in its movement the bar 26 as well as the pivot 24 of the lever 26, whilst the bar 28 with its abutments will have been displaced in a contrary direction, so that in reality a relative movement has taken place between the arm 34 and the abutments 29, 3|). The adjustment of the abutments must therefore be eiected in acordance with this relative displacement.

If now, owing to an excess of play of the brake shoes, the braking action is not perfect, the different members will continue their movement, with the exception that the exterior cylinder or box 35 of the device will be held back by means of its setting member or arm 34 applied against the abutment-nut 30, this box in its course correspondingly holding back the clamp 32 'through which the threads 33 of the bar 26 will now slide. In the manner set forth above, a relative displacement will accordingly take place between the box 35, pushed to the left in the drawings by the bar 28, and the interior tube or box 31 of the clamp 3| adjusted relatively to the right, the space 40 occuring now between the exterior box and the interior box in the axial direction, being at this moment an indication of the excess of the total play, not only of the shoes controlled by the bar 26 but also of these controlled by the bar 21.

The braking action over, only a return relative movement, equivalent to a normal braking action, can of course take place between the device and the abutments 29, 3U, after which the exterior box 35 of the device will be blocked by the abutment 29, and only the interior box 31 Will continue its return movement as described in regard to the rst form of the invention, by shortening the bar 26, by a length corresponding to the Width of the space 40. It is this last nal position that is shown in Fig. 6, in which the threaded part 33 is seen to enter more deeply into the cylindrical bore 4I of the box 31.

'Ihe return of the various members to the inoperative position may be effected by springs outside the device, but may also as shown in this second form of the invention, be effected by an interior spring 42.

Moreover if desired such a spring may be placed in the first form of the device, in the ring-shaped space 43 of Figs. 1 and 2.

As shown in the drawings the clamps 4, II, 3I and 32 consist of co-operating parts or sections yieldingly held together by means of elastic members 4a, Ila, y3Ia and 32EL respectively.

What I claim is:

In an automatic play take-up device for brake rigging, the combination of an outer casing, an inner casing telescopically combined with said outer casing, a conical stop on each of said casings, a flat stop on each of said casings in opposed spaced relation to the conical stop thereof, a threaded bar projecting into said casings and constituting part of the brake rigging, clamps located within said casings in operative relation to said threaded bar, said clamps each consisting of a plurality of sections held together by an elastic member and being movable between the stops of the respective casings and co-operating therewith to respectively grip and release said thread bar, a pair of double levers constituting part of the brake rigging, one of said casings being connected with one of said levers, two spaced abutments carried by the other of said levers, and a setting member carried by the other casing and movable between said spaced abutments, said setting member in co-operation with said pair of abutments being arranged to shift said casings 

